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pulls when braking, active handling on when turning left
Could you folks help me figure this out??? Car is a 2004 Z06. Here are the symptoms:
1. Car pulls left when braking
2. Active handling activates when turning left
3. TCS codes were c1247H and c1281H, cleared them and did not come back after a 10 minute drive
4. Car won't start the first few times I turn the key but eventually it will. Battery is fully charged and all accessories are working strong when this happens
Not sure if any of these symptoms are directly related but wanted to share them all just in case they are related in some way.
Thanks in advance for any help.
Happy New Year !!...if you look above this thread you'll see another member has similar issues like yours...you sure it's a 1247 ??...the C1281 DTC may have set because of the car pulling left when you brake...I'd check the simple things...tire pressure, warped rotor, sticking brake caliper, loose suspension components, wheel alignment etc...if the EBCM senses the front or a$$ end braking free in a sharp turn the EBCM is supposed to apply the left or right brake to keep this from happening...a scan tool would really be helpful to look at some data PIDS output voltages...parts that can be bad is steering wheel position sensor, EBCM, and the yaw or lateral acceleration sensors.
Now how the heck did you know you have 2.5 volts ???...scan tool ???...this is my ‘01 centered and 11:30 !!...and yes should be “roughly” 2.5 volts when the wheel is centered and as you can see you have 2 input voltages for the SWPS !!...I checked my FSM for the other DTC (C1247) and it refers to brake fluid level...my Mitchell program didn’t even list the DTC !!
Without even unplugging the swps from the car, I inserted 2 thin paper clips into the back of the connector...one on the top connector which is blue and the other on the bottom connector which is grey. Started the car connected my voltmeter to them...red to the paper clip connected to the blue wire and black to the paper clip on the grey wire. That gave me the readings I was looking for. Turned the wheel all the way to the left and got a reading of 5.02v and then all the way to the right gave me a reading of .35v. Then I centered the steering wheel perfectly and it was low. Can't remember exactly what the number was but turned to the left a little bit at a time until i got a 2.5v reading and it was about at the 11:30 position. This seemed to work...is this not an accurate way of testing this???
OK, Great !!...so you have some electrical skills...if I were you I'd chase the braking issue first !!...the light blue wire is the signal B and light green is signal A...you using the wiring schematic from the FSM ????
My electrical skills are poor at best. I figured out how to test it that way by reading on this forum. Do you think that there is any way that the car is pulling to the left when I hit the brakes because my swps is not perfectly centered??
If your car was pulling right or left WITHOUT touching the brakes you can have issues with the SWPS, WSS, EBCM, or lateral or yaw accelerometers !!...if it pulls just when applying brakes you have some kind of mechanical issue going on...I had listed them previously.
IIRC, AH uses the abs to pulse the brakes usually in response to a yaw signal and the swaps position. So it really should only activate in a turn or a skid. Usually it activates too late to get you out of a jam, but that is another story. The only message is on the DIC. No codes will be tossed if you activate AH, unless it is associated with a fault. I think the yaw rate module is under the driver seat, and I don’t have any experience with them going bad
So I’m with C5 Diag on this, and offer this. The brake fluid in the ABS part of the braking system is on the order of 16 yo unless it has been cycled out. A scan tool with bi-directional control is needed to flush abs. A regular brake bleed won’t help. It could be that you have a gummed brake line or a hung caliper. Maybe a gummed abs line as well. The flex hoses at each wheel can delaminate and form a spot that restricts flow on one wheel. Usually you will see a bulge in the line. air in one caliper is another really likely cause
Recent alignment? C5’s are really simple to align, but if thrust is off the car will pull on braking. Because most roads are crowned for good rain runoff, a properly aligned car will SLIGHTLY pull to the right on braking, not the left.
K24556, thank you for taking the time to respond. I really appreciate it. I will definitely be checking into all of these suggestions in the coming days and will report back with my findings or any additional questions.
another thought. A bad wheel bearing can cause poor wheel speed sensor output, which can affect abs actuation, especially at very slow speeds. Even a bad electrical connection can mess up wsu’s signals, and this is common on C5’s. The connectors are weatherpack, but moisture can get in and give the connection the green crud (corrosion).
If the wheel bearing is bad enough to mess up wsu’s signals, then you can check by jacking a wheel off the ground and trying to move it in and out. If it wiggles, bad wheel bearing
So far I have disassembled the brakes, inspected them, and checked the temperature of the brakes after a drive. The brakes look fine including the lines. All suspension parts look good. There was a 10 degree difference between the front brakes after driving...the right being 10 degrees cooler.
I just invested in a Tech 2 scanner. I have never used one before. Any suggestions on what to look at on the scanner to figure this out? Also, is there a way to center my SWPS with the Tech 2?
Thanks!
OK. Here are your 4 issues from your original post:
1. Car pulls left when braking
2. Active handling activates when turning left
3. TCS codes were c1247H and c1281H, cleared them and did not come back after a 10 minute drive
4. Car won't start the first few times I turn the key but eventually it will. Battery is fully charged and all accessories are working strong when this happens.
Let's see if we can solve these one at a time. Later if you need the tech 2 or a multimeter, we may need to pull some wiring diags and guide you through how to use it.
Since you cleared codes and the codes listed in #3 didn't come back, put that one on the back burner for the moment. Also, put the hard starting issue back for the moment.
. 1. Car pulls left when braking.
Q1: When you are on a perfectly flat driving surface (e.g: parking lot with no cars) does the car pull to the left with light braking?
Q2: Any messages show up on the DIC when you light brake?
Q3: when you are on the perfectly flat surface, and you are at 30MPH, driving in a straight line, let go of the steering wheel, and SLAM on the brakes, does ABS activate and does it pull to the left? (Don't be a wussy, SLAM in the brakes to purposefully activate ABS. Put that friggin' brake pedal to the wall) Please let us know results. You should see a brief message on the DIC about ABS that goes away.. Now let us know of any result. If the parking lot you chose is wet, so much the better, we need to know how the car responds.
Now if you are on a flat surface with NO slope what so ever, and the steering wheel at 0deg, does the car stay in a straight line when driving it? If not then FIRST get a good alignment and make sure rear thrust is ZERO, and both front and rear toe are ZERO (you can ask for camber settings that suit your needs, but -0.6deg camber front and rear will be okeydokey for the street). Do not accept the alignment results that just put the numbers withing spec. ZERO toe, ZERO thrust.
OK. Here are your 4 issues from your original post:
1. Car pulls left when braking
2. Active handling activates when turning left
3. TCS codes were c1247H and c1281H, cleared them and did not come back after a 10 minute drive
4. Car won't start the first few times I turn the key but eventually it will. Battery is fully charged and all accessories are working strong when this happens.
Let's see if we can solve these one at a time. Later if you need the tech 2 or a multimeter, we may need to pull some wiring diags and guide you through how to use it.
Since you cleared codes and the codes listed in #3 didn't come back, put that one on the back burner for the moment. Also, put the hard starting issue back for the moment.
. 1. Car pulls left when braking.
Q1: When you are on a perfectly flat driving surface (e.g: parking lot with no cars) does the car pull to the left with light braking?
Q2: Any messages show up on the DIC when you light brake?
Q3: when you are on the perfectly flat surface, and you are at 30MPH, driving in a straight line, let go of the steering wheel, and SLAM on the brakes, does ABS activate and does it pull to the left? (Don't be a wussy, SLAM in the brakes to purposefully activate ABS. Put that friggin' brake pedal to the wall) Please let us know results. You should see a brief message on the DIC about ABS that goes away.. Now let us know of any result. If the parking lot you chose is wet, so much the better, we need to know how the car responds.
Now if you are on a flat surface with NO slope what so ever, and the steering wheel at 0deg, does the car stay in a straight line when driving it? If not then FIRST get a good alignment and make sure rear thrust is ZERO, and both front and rear toe are ZERO (you can ask for camber settings that suit your needs, but -0.6deg camber front and rear will be okeydokey for the street). Do not accept the alignment results that just put the numbers withing spec. ZERO toe, ZERO thrust.
After an alignment, then go through Q1-Q3.
Thank you for you input! I will read through your attachment later tonight. I did do the ABS test a few days ago and just checked to see if the ABS was functioning properly and it was. I don't recall if it pulled while the ABS was activated. I will try that again. As well as the alignment test.
On another note...I just got in from messing with the car. I hooked the tech 2 up and got readings from my SWPS. When I tested it with my multimeter I only tested at center, full left, and full right because of the crazy position I was in trying to do the test. The multimeter values from the other day made it seem like the sensor was working correctly. Tonight, with the Tech 2, I watched the values all the way through the turns of the steering wheel. While my multimeter readings were correct at full left, center, and full right, on the Tech 2 was getting values going all the way up to 5v and down to 0v when turning from center in either direction. Looks like the sensor is shot.
So now my plan will be a new SWPS and alignment. I will report back soon.
Thanks!
Here is the schematic for the SWPS. I think (not totally sure) that if you read between pin A and L with the steering wheel centered you should see 2.5v DC. Then between H-L the same reading, 2.5V. Then if you turn the steering wheel, either A-L or H-L should go to 0, and the other should head towards 5V. So I think your T2 says SWPS is Ok
As a further note, pin L is “Low Reference” on the diag I just posted. LowReference is a common O VDC connection in the pcm. I’m not totally sure it is tied to chassis ground, so be really careful probing around the 5 V stuff. Also note there is a feed to am Active handling circuit from the SWPS, so there will be some computing going on with that signal.
If you haven’t already done so, lifting the battery ground will reset a lot of stuff. It could make your problem go away. C5Diag might have a thought about this. IIRC, leaving it disconnected 20 minutes forces a lot of re-learns
pulls when braking, active handling on when turning left
